Lowest Cost Dynamic Lighting

What would be the lowest GPU demanding lighting setup using a Light Source, Sky Light and SkySphere?
Asking for a VR project, very large, lots of sub-levels. Have attempted static lighting but not only are there only no dynamic shadows for my animated actors but some of sub-levels are so large they take days to production build, and even then a few have crashed, making me think dynamic lighting could be the better option. Thanks!